Wiring a Showcase Planetarium

Supporting lighting and interactive displays in this state-of-the-art renovation, 1.2 million feet of power and low-voltage control wiring bring to life New York's Rose Center for Earth and Space.There are no seat belts in the Space Theater at New York City's American Museum of Natural History, but some visitors might find them useful. Why? Because in just half an hour, they will zoom from W. 81 superscript

Supporting lighting and interactive displays in this state-of-the-art renovation, 1.2 million feet of power and low-voltage control wiring bring to life New York's Rose Center for Earth and Space.

There are no seat belts in the Space Theater at New York City's American Museum of Natural History, but some visitors might find them useful. Why? Because in just half an hour, they will zoom from W. 81 superscript st Street in Manhattan to the far reaches of the universe and back.

"We built this virtual world, the largest virtual-reality system anywhere, to take people on a fantastic voyage that even excites scientists," says Dr. James Sweitzer, Director of Special Projects at the new Rose Center for Earth and Space at the north end of the museum site.

Now referred to as a "cosmic cathedral," this magnificent museum was years in the making. What began as a simple renovation for E-J Electric Installation Co., Long-Island City, N.Y., turned into a $210 million, fast-track design build project. The electrical work alone jumped to $21 million by the end of the job, says Tony Mann, president of the electrical contracting firm.

E-J Electric performed all the lighting, power, and communications work for the Rose Earth and Space Center, a state-of-the-art museum built on the site of the world famous Hayden Planetarium. Built in 1935, the structure started to show a few sags and wrinkles after years of heavy tourist traffic. Rather than making surface improvements, Ellen Futter, president of the American Museum of Natural History, decided to have it torn down and rebuilt in 1996.

Replacing the planetarium's original 1930s Art Deco structure, the center includes the Cullman Hall of the Universe, Gottesman Hall of Planet Earth, and centerpiece of the 333,500-sq-ft, seven-floor high glass cube (an 87-ft diameter sphere that houses the Space Theater). The white, aluminum-clad sphere appears to float inside the 95-ft-high glass cube with planets hanging elegantly around it.

With few artifacts to show, the exhibit designers rely on 3-D computer modeling, video walls, and sound loops to reach audiences that range in age, interest, and education. To support the visual and aural stimulation, the project team for E-J Electric Installation Co., Long Island City, N.Y., had to plan out various wiring methods to contain the more than 230 miles of electrical power and low-voltage control wiring needed on this fast-track design/build project.

According to E-J Project Manager Mitchell Olshewitz, as the project developed so did the owner's concept of what the building should do and how it should perform. This methodology had tremendous impact on the electrical scope of work.

As a result, electricians had to work carefully to blend the electrical components into this unique but limiting architectural design. The museum was exceptionally challenging from a coordination standpoint because installers could only run conduits in defined locations. There was limited ceiling and equipment space and severely congested shaft space with the work of the other mechanical trades.

Olshewitz notes that the only electrical and mechanical piping entrance into the spherical planetarium structure is through several horizontal ellipsoidal tunnels. These tunnels had to be manufactured to exacting architectural tolerances with limited space available to trades. He says there was absolutely no room for error, and the team spent many hours coordinating every step because fractions of inches were critical.

"The crawl space under the Space Theater is horrendous," he says. "That's where the structural web for the whole theater sits. The crawl space varies in height between 5 ft to a low point of about 36 in. It is a maze of duct work and mechanical and electrical piping and equipment."

While metal conduit runs and ladder-type cable trays carry much of the wiring, the contractor used wire basket cable tray within wiring closets and electronic equipment rooms. Installers could easily bend the wire basket stock on the job site to conform to field conditions. Olshewitz notes this type of flexibility is critical in today's fast-track design/build construction environment. Now, more than ever before, electrical contractors must make decisions on cable support systems, and use experience and judgement in specifying and setting up cable support hardware.

A particularly interesting part of the job involved placing the fiber optic network cabling. The fiber network uses 96 multimode fibers and 48 single-mode fibers to connect the supercomputer to the Space Theater control console. The electrician/installers received special training from the cable manufacturer to assure low loss splices and connections.

Illuminating the universe. Although the facility makes wide use of standard architectural lighting control systems, it also employs a number of theatrical lighting fixtures. A special lighting control protocol standard, known as DMX 512, controls these fixtures. This system relies on a special cable construction that contains either two or four conductors and a ground. Using a daisy-chain topology, a single cable can support a large number of dimmers. Therefore, it has greater versatility in terms of control and supervision.

The Space Theater uses an ETC Unison theatrical dimming and control system, along with a DMX distribution system for special events. Additionally, an emergency lighting transfer system and contact closure interface provides a link with the life safety and A/V systems. For the pre-show area, the facility uses an ETC architectural control system. A contact closure interface also links the life safety and A/V systems, and a group of alternate source transfer switches serve as a cost-effective means of switching normal power to emergency power.

At the Hall of the Universe, fluorescent light sources illuminate the display panels and cutout texts used within the educational exhibits. About 200 fluorescent circuits serve the displays, and the staff can dim each circuit down to about 1% of output. Thus, in most cases, designers dedicated a 15A branch circuit to a single fluorescent fixture. Since power consumption per circuit is about 300A, most of the branch circuit loads are less than 60W.

Since conventional SCR dimming does not operate well under low loads, the contractor chose special fluorescent dimmer ballast controller cards. Each card receives a DMX signal that can power four 15A circuits. Similar dimmer racks handle incandescent load dimming. The team used low-voltage relay panels with DMX interfaces and relay drivers for controlling power to fiber optic illuminators and LED controllers.

Three 5-ft-deep pits, or wells, located beneath the exhibit hall house these dimmer racks and control panels. Since the pits are too shallow to accommodate full size dimmer racks, the contractor used smaller, custom-designed racks and panels. The exhibit lighting in this area operates through an architectural control system, and a contact closure interface connects with the A/V system and the life safety system.

The lighting around the sphere is especially interesting. Linear fluorescent floodlights mounted in rows above and below the sphere bathe it with a blue glow. Louvered to minimize source brightness, these fixtures use 4-ft, T12 lamps, which have a 20,000-hr average-rated life.

A number of spherical objects placed near the seven-story high sphere illustrate the relative size of the planets and other elements in the solar system. Hung from the ceiling and affixed to railings, they link to educational messages. For example, one plaque says: "If the sphere is the sun, then this 9-in. ball is the earth."

This museum is the first major public building to use what we call an "events lighting system," which allows portable theatrical lighting equipment to come in off a truck and hang without stringing out a lot of portable power and control cable across the floor. Recessed floor boxes and wall boxes with custom faceplates pick up 120V and 208V power and control circuits at convenient locations in the Hall of the Universe. This allowed installers to hang up to 20 portable dimmer boxes at any of the lighting positions and plug them into a DMX control station to provide special events lighting.

On large-scale projects like this one, John Ranagan, general foreman for E-J Electric, offers some advice for electrical contractors. First of all, watch the dates that you agree to, especially if you don't have all of the information. Make sure you have a workforce readily available, and coordinate the materials and labor. Work closely with the general contractor, architects, and engineers, and most of all, expect the unexpected.

About six months after the grand opening of New York's Rose Center for Earth and Space, the planetarium continues to attract big crowds. "I think attendance has exceeded expectations, says Olshewitz. "There's a lot of tourists here every single day. There are areas that are still being designed that have not been completed. It's an ongoing process."

Sidebar: Electronic Technology Shines

Housed in the top portion of the 87-ft-diameter sphere is the 432-seat Space Theater. Within this theater, visitors sit in high-backed auditorium chairs with headrests and look up to the images projected on the hemispheric surface. Made of perforated aluminum panels with an off-white color, the dome serves as a scrim for the projected light images. The scrim is several feet in from the outer surface of the sphere, and the space in between the two surfaces contains a network of conduits enclosing miles of power and communications cabling. The space also holds scaffolding and catwalks used for equipment maintenance.

With Tom Hanks narrating, the show starts with an earth-centric look at the Milky Way from a custom-built projector, which sends white light through fiber optic cables to produce the effect of 9100 stars. After these images fade, the second imaging system takes visitors on a dazzling journey through a 3-D universe. These images, produced by a bank of seven high-definition video projectors mounted around the perimeter of the dome, create a fantastic spectacle that guides the viewer through the Milky Way and star systems/galaxies beyond our own.

Producing 7.34 million pixels in combination, the video projectors receive digital data streams from a visual workstation. Equivalent in power to those used by NASA or the largest military research laboratories, the supercomputer, with its 28 processors (along with a large data storage array containing up to two terabytes [2000 gigabytes] of digital information) can simultaneously process 14 gigabytes of data. A fiber optic cable network sends the data from the supercomputer to each of the seven TV projectors, a distance of several hundred feet.

The sound system provides directional sounds, and subwoofer speakers installed at floor level provide a sense of movement and a sensation of "lift off" at the start of the space journey presentation.